Method and an apparatus for the manufacture of concrete pipes

ABSTRACT

A method and an apparatus for the manufacture of concrete pipes ( 2 ) made of an outer layer and having an inner layer of greater density in surface structure is described. The inner layer is applied by an applicator in a mould ( 1 ) having both outer ( 3 ) and inner ( 4 ) mould parts. The applicator is formed by an inner mould part or core ( 4 ) or by an applicator unit in immediate connection with the core ( 4 ). The applicator applies the inner layer simultaneously or immediately following vibration of the concrete forming the pipe. The inner layer is applied during movement of the inner mould part or core ( 4 ) in its longitudinal direction, the core having one or more supply openings ( 14 ) provided along the circumference of the core ( 4 ) at the upper end of the core ( 4 ) for supplying a further material of greater density to form the inner layer.

TECHNICAL FIELD

The invention relates to a method for the manufacture of concrete pipesmade of an outer layer, said outer layer forming the pipe itself, aswell as an inner layer of greater density in surface structure, theinner layer being supplied by an applicator in a mould having inner aswell as outer mould parts.

The invention also relates to an apparatus for the manufacture ofconcrete pipes using an applicator formed by an inner mould part or core(4) or by an applicator unit in direct connection with the core, theapplicator supplying the inner layer simultaneously or immediatelyfollowing vibration of the outer layer.

BACKGROUND

Concrete pipes, which are normally used for the discharge of wastewatervia sewers as well as for the discharge of rainwater, are generallymanufactured such that the pipe exclusively consists of the baseconcrete which is used for the casting of the pipe.

Since the development within the field of environment and wastewater hasinvolved the separation of wastewater and rainwater, rainwater by-passesthe cleaning systems passing through separate conduits to reduce theload on the wastewater cleaning systems, a concentration of thewastewater increases at the same time, which means that the wastewateris even more corrosive for the concrete pipes than before.

To prevent the corrosive wastewater from attacking the concrete pipes,it has been attempted to line the pipes with a material other thanconcrete for the manufacture of what is called lined pipes. Such alining may be carried out in several different ways, but generally it isdone in that the lining is placed on the core in the mould, followingwhich the concrete pipe is cast and removed from the mould in aconventional manner, which means that the cast pipe and the outer formare lifted off the core, and the outer form is lifted off the pipe.

In addition to increased manufacturing costs and problems of densitywhen joining the pipes to a conduit, this also involves a reduction ofthe capacity in the manufacture of such pipes. U.S. Pat. No. 5,051,223discloses another method of manufacturing corrosion resistant concretepipes. Here, use is made of a radial pressing head which is basicallycomposed of a plurality of oppositely running rolls which form theinternal part of a concrete pipe. The external part is formed in anordinary manner by means of an outer form.

Concrete is poured into the mould, while the radial pressing head is runup through the vertically positioned outer form. When the radialpressing head with its oppositely running rolls runs up through theouter form, these oppositely running rolls form the inner surface of thepipe. A smoothing device is provided at a fixed distance after theoppositely running rolls, seen in the direction of travel of the radialpressing head, an impregnation liquid supplied to the internal surfaceof the concrete pipe by the smoothing device. This impregnation liquidis supplied while the concrete is still wet, whereby the impregnationliquid in the subsequent smoothing permeates about 10 mm into the innersurface of the pipe wall. This subsequent smoothing, also calledpolishing, takes place after the pipe has been formed.

Today, however, a large number of concrete pipes are manufacturedaccording to a different method, viz. by the so-called vibration method.For this manufacturing method, it is not possible to use theabove-mentioned known technique for the manufacture of corrosionresistant concrete pipes.

In the manufacture of concrete pipes according to the vibration castingmethod, the technique may again be divided into two methods, viz. themethod with a rising core and the method with a fixed core.

In the rising core method, as shown for example in European Patent No. 0674 573 B, the casting machine comprises a casting mould which basicallyconsists of an outer formwork in the form of an outer form, an innerformwork in the form of a core, a bottom formwork in the form of abottom ring and a feed system. In addition, there is a profile ring forthe forming of the spigot end of the pipe, defining the upward boundaryof the casting mould.

In the making of the pipe, vibration is applied via vibration meanswhich may be arranged in the core, on the outer form or as tablevibration, where the core or outer form stands on a vibrating table.

In the manufacture of a pipe according to the rising core method, thecasting process basically takes place in that the core is moved upthrough the bottom ring, following which it is stopped, the core beingpresent at a certain height in the mould. Then, concrete is poured intothe mould from its upper part. Subsequently, the core is movedcontinuously up through the mould while concrete is being filled intothe mould. The concrete is distributed and compacted during the processby a rotor arranged on the top of the core, while the concrete isvibrated under the action of a strong vibrator, normally arrangedcentrally in the core. A profile ring is arranged at the upper end ofthe outer form, and when the mould is filled with concrete, this profilering defines the upper boundary of the mould, together with the outerform and the core. When the mould has been filled with concrete,pressing is performed, and then the profile ring is rotated slightly toand fro in order to smooth the spigot end. One of the effects of thiscasting process is that it ensures that the manufactured pipes have thesame length.

In the manufacture of pipes according to the fixed core method, thecasting process basically takes place in that the core is fixedlypositioned, and that an outer form having a bottom ring clamped theretois arranged over the core. The concrete is then poured down into themould from above, while vibration is applied to the mould. When themould has been filled, a profile ring is moved down at the top of themould, and thereby the spigot end of the pipe is formed. Then the coreis removed from the mould by means of a crane or similar lifting toolwhich positions the pipe, bottom ring and outer form for setting at asuitable location, where the outer form is loosened from the bottom ringand the crane lifts the outer form off and away.

Accordingly, the object of the invention is to provide a method ofmanufacturing concrete pipes with an inner surface, where the propertiesare improved with respect to surface quality, e.g. in that the innersurface exhibits a greater corrosion resistance, better flow propertiesand a more attractive surface structure.

A further object of the invention is to provide an apparatus for themanufacture of such pipes.

The method of the invention, ensures that when the pipe itself has beenformed, a further layer of greater structural density is applied to theinner side of the pipe through the inner mould part, the so-called core,via nozzles or gaps, while the mould and thereby the concrete arevibrated. Vibration of the mould keeps it in a form of a fluid phase.When the concrete is maintained in such a fluid phase during the feedingof material of greater structural density, the effect is achieved thatthe two materials merge to a mutually denser structure, therebyproviding a tighter bond between the two materials.

An advantageous way of feeding the material of greater density instructure, is by feeding the further material through the inner mouldpart, the core, while it is displaced into the outer mould part, feedopenings being provided in the core along its circumference at the upperend of the core for the supply of the further material.

A method is described where the applicator in the apparatus is formed bya core which is rotated after the forming of the pipe, a further layerbeing applied internally to the pipe from one or more rows of nozzles.In this case, the apparatus for the performance of the method ispreferably of the fixed core type.

A method is described where the applicator for the application of theinner layer is formed by the rotor, which is also used for forming thepipe beforehand. At its lower part, the rotor is provided with one ormore supply openings for the further material.

A method is described where the inner layer is applied to a top and/orbottom ring before these are applied to the other mould parts. Thisensures that the parts of the finished concrete pipe which willconstitute the parts to be joined in the laying of a pipeline, also havea surface of greater density than the outer surface of the concretepipe.

A similar method is also described but where the further layer isapplied to the bottom and/or top ring after the bottom and/or top ringhas been connected with the other mould parts, and before the mould isfilled with concrete.

An embodiment of the method is also described where the spigot end ofthe pipe is provided with the further material to form the inner layerof greater structural density.

The further material may be fed in the form of a paste, powder orliquid.

An apparatus is defined for the performance of the method, where thecore, according to the rising core principle, constitutes theapplicator. The further material is fed through one or more annulargrooves, said grooves extending along the circumference of the core andbeing arranged at the front end of the core seen in the direction oftravel of the core.

An apparatus is also defined with an applicator for a core according tothe rising core principle, where the annular groove or grooves areformed with a plurality of nozzles or gaps for the supply of the furthermaterial.

An apparatus is also defined with an applicator according to the fixedcore principle, where the core is rotated after or during the forming ofthe pipe. The core is provided with one or more grooves which extend inthe longitudinal direction of the core, said groove or grooves extendingin the entire effective length of the core. The further material is fedthough the groove or grooves adapted for the purpose, while the core isrotated about its longitudinal axis. The core is rotated at least enoughso that the entire inner surface of the pipe is covered by the furthermaterial.

The apparatus as described above may have the groove or grooves extendas straight grooves in the longitudinal direction of the core.

The apparatus may have the groove or grooves extend in a form of aspiral along the surface of the core in the longitudinal direction.

An apparatus is further defined where the applicator is placed on arotor in the lower part thereof, so that the further material is fed tothe inner surface of the pipe by means of a plurality of nozzles orgaps, just after the pipe itself has been formed.

The further material is preferably fed under pressure and while themould and/or pipe are vibrated. The pressure may be provided by thesupply of the further material, or may optionally be applied by anexpedient configuration of the core in connection with the provided gapor gaps in the surface of the core.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described more fully below with reference to thedrawing, where

FIG. 1 shows an apparatus for the casting of concrete pipes with aninner layer of greater density in structure, where the applicator isformed by a longitudinal gap in the core,

FIG. 2 shows an apparatus for the casting of concrete pipes with aninner layer of greater structural density, where the applicator in thecore is formed by a longitudinal gap with a plurality of nozzles,

FIG. 3 shows an apparatus for the casting of concrete pipes with aninner layer of greater structural density, where the applicator isformed by a gap twisted along the surface of the core with a pluralityof nozzles in the gap,

FIG. 4 shows an apparatus for the casting of concrete pipes with aninner layer of greater structural density, where the applicator isformed by the lower part of the rotor,

FIG. 5 shows an apparatus for the casting of concrete pipes with aninner layer of greater structural density, where the applicator in thecore is formed by a gap which extends along the circumference, and whichis present in the upper end of the core, and

FIG. 6 shows an apparatus for the casting of concrete pipes with aninner layer of greater structural density, where the applicator in thecore is formed by a gap which extends along the circumference, and whichhas a plurality of nozzles therein and is present at the upper end ofthe core.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the invention are now described, where use ismade of a casting mould 1 for the casting of a concrete pipe 2, thecasting mould 1 comprising an outer formwork in the form of an outerform 3, an inner formwork in the form of a core 4, a bottom formwork inthe form of a bottom ring 5, a top formwork in the form of a profilering or top ring 6 for forming the spigot end 7 of the pipe 2, and afeed system 8 for the supply of concrete 9. Vibration is applied inconnection with the casting mould. This is done in a preferredembodiment by means of a vibrator 12 preferably arranged in the core 4.The vibration may be applied from an external source of vibration andoptionally from a vibration table.

When a pipe 2 is to be cast by means of the rising core principle, thisroughly takes place in that concrete 9 is poured via the feed system 8into the mould 1, where the outer form 3 rests on the bottom ring 5which stands on a substrate 13. The rotor 10 is rotated about alongitudinal axis which extends through the center of the core 4. Whenrotating, the rotor 10 presses the concrete against the inner side ofthe outer form 3, whereby the pipe 2 is formed, while the core 4moves—rises—into the outer form 3. The vibration from the vibrator 12contributes to making the concrete 9 more uniform and dense. The lengthof the pipe 2 is determined by the position of the profile ring 6 in theouter form 3, and when the rotor 10 passes through the profile ring 6,it simultaneously casts the spigot end 7 of the pipe 2, which ensuresthat the pipes 2 have a uniform length. The surface of the spigot end 7is finished in that the profile ring/top ring 6 is rotated and pressedon to the spigot end 7 of the pipe 2, the spigot end 7 being smoothedthereby.

A pipe may also be cast according to a fixed core principle. Thisprinciple differs from the rising core principle in that the core hasbeen placed in the mould in advance and is not movable in itslongitudinal direction. When the concrete is poured into the mould bygenerally used distribution means, said mould consisting of a core,outer form, bottom ring and top ring, vibration is applied from avibrator, which is preferably arranged in the core, but may also beapplied from an external vibrator or optionally from a vibration table.

According to the invention, a plurality of nozzles and/or gaps 14 areprovided on the core 4, in case of the rising core as well as the fixedcore, to supply a further material, so that the further material issupplied to the internal or inner surface of the concrete pipe 2 justformed.

To ensure that the spigot end 7 and the socket 15 of the pipe 2 are alsoprovided with a further material, the further material may be suppliedto both the profile ring 6 and the bottom ring 5 before they are appliedto the outer form 3. This may be done by supplying the further materialby supply means from the core 4, from the outer form 3 or optionally byprecoating the profile ring 6 and/or the bottom ring 5. The supply ofthe further material to the spigot end 7 may also take place in that theprofile ring 6 is lifted and then the further material is filled bysupply means over the spigot end 7 of the pipe 2, following which theprofile ring 6 is lowered or pressed down over the spigot end 7simultaneously or immediately following the vibration.

In a preferred embodiment of the arrangement of nozzles and/or gaps 14on the core, as shown in FIGS. 1 and 2, the nozzles and/or gaps 14 arearranged in the longitudinal direction of the core 4, and the furthermaterial is fed to the pipe 2 by rotation of the core 4 about itslongitudinal axis.

In another preferred embodiment of the arrangement of nozzles and/orgaps 14 on the core 4, as shown in FIG. 3, the nozzles and/or gaps 14are arranged in a groove which is twisted in a form of a spiral orthreads in the longitudinal direction of the core 4. Here, too, thefurther material is fed to the inner surface of the pipe by rotation ofthe core 4 about its longitudinal axis. In this case, the rotation mayoptionally be supplemented by a movement in the longitudinal direction.

The embodiments of the arrangement of nozzles and/or gaps on the core 4according to FIGS. 1, 2, and 3 may advantageously also be used in thesupply of the further material with the fixed core casting principle. Inthis case, the core will then be positioned in the casting mould, andafter the mould has been filled with concrete 9, the core 4 will berotated about its own longitudinal axis either during vibration orimmediately following vibration, while the further material is suppliedthrough the nozzles and/or gaps arranged in the core 4.

The core is rotated such that the row or rows of nozzles supplying thefurther material to the pipe are moved precisely so far that thesupplied material covers the entire inner side of the pipe.

In a third preferred embodiment of the arrangement of nozzles and/orgaps 14, as shown in FIG. 4, these are placed on the rotor 10 on thelower end thereof, so that the supply of the further material takesplace during the rotation of the rotor 10. The rotor 10 is provided withsuitable means (not shown) for providing a plurality of nozzles and/orgaps with the further material which is to be applied to the innersurface of the pipe 2. The supply may take place through channels formedin the blades 11 of the rotor 10, or through supply channels extendingfrom an area near the center of the rotor 10 to an area near thecircumference of the rotor 10.

In a fourth preferred embodiment of the arrangement of nozzles and/orgaps 14, as shown in FIGS. 5 and 6, these nozzles and/or gaps arearranged in an annular groove 14 which extends along the circumferenceof the core 4. The annular groove 14 is preferably arranged at the frontend of the core 4 in the direction of travel of the core 4. In case thatit is not possible to move sufficient material through this one annulargroove 14, several annular grooves may be arranged in the immediatevicinity of the first annular groove

Supply of the further material during or immediately following vibrationprovides the effect that the further material is joined with theconcrete in such a manner that a form of diffusion of the two materialsinto each other occurs, so that a type of sliding transition from theconcrete and out into the further material takes place. This ensures astrong bond between the joined materials.

When a pipe has been cast, it is removed from the mould in the usualmanner, which means that with the rising core principle the core ismoved down to the starting position, the profile ring at the top of thepipe and the outer form are removed so that the pipe stands on thebottom ring ready for transport to a setting area or the like. Here, itmay be decided to allow the profile ring to remain on the top of thepipe during the finish setting to achieve even better tolerances on thespigot end of the pipe. This, however, will require use of more profilerings.

When removing the pipe from the mould with the fixed core principle, thepipe, bottom ring and outer form are lifted off the core by means of acrane and are placed in a setting location adapted for the purpose. Atthe setting location, the outer form is loosened from the bottom ring,and the outer form is lifted off the pipe by a crane or the like.

In an optional further embodiment, it is conceivable that the furthermaterial is supplied only to a portion of the circumference of the pipe,so that the further material just covers the inner part of the pipe,which will face downwards when the pipe is positioned substantiallyhorizontally with the inclination required for the flow of water,wastewater or the like. In the rising core embodiment, this mayoptionally be done by blocking the part of the gap or the nozzles whichare not to receive any further layer. In the fixed core embodiment, itis sufficient to rotate the core just one half of a rotation or as faras is found necessary. In the embodiment where the applicator is formedby the rotor, the supply to the nozzles may be blocked in a controlledmanner, so that the further material is just fed through the nozzleswhen the nozzles are at the area to which the further material is to besupplied.

1. A method for manufacturing a lined concrete pipe comprised of an outer concrete layer and an inner liner layer containing a further material which forms a greater density inner surface liner, said method comprising: providing an outer mould part and a core, a space formed between the outer mould part and the core having a shape of the lined concrete pipe, the core being movable upwardly through the outer mould part; providing a vibrator within the core, feeding concrete to the space formed between the outer mould part and the core as the core moves upwardly within the outer mould part for filling the space with concrete, providing the core with an applicator comprising one or more supply openings positioned for delivering the further material below the concrete supplied to the space, vibrating the concrete filling the space between the outer mould part and the core for maintaining the concrete in a fluid phase as the concrete is filling the space while simultaneously supplying the further material through the supply openings of the applicator for merging and diffusing the further material into the adjacent fluidized concrete, and at least partially rotating the applicator and the core during delivery of the concrete and further material for merging and diffusing the further material into the concrete adjacent the applicator to provide a sliding transition from the concrete and out to the further material, forming a mutually denser structural liner with a tight bond, the liner integrating together the concrete and further material, thereby forming an integral liner with the concrete pipe, providing a greater density surface on at least a portion of an inner surface of the concrete pipe; and, delivering the further material for applying an inner layer to a bottom ring and/or a top ring and then applying said ring or rings to the core and the outer mould part.
 2. The method of claim 1 wherein the applicator is integrally formed with the core or by an applicator unit in direct connection with the core.
 3. The method according to claim 1 wherein the further material is delivered in the form of a paste, powder or liquid.
 4. The method according to claim 1 wherein the one or more supply openings essentially extend in the longitudinal direction of the core.
 5. The method according to claim 1 further comprising forming the core with the one or more supply openings located along the circumference of the core at an upper end of the core.
 6. The method according to claim 1 wherein the applicator is in a form of a rotor, the rotor having the one or more supply openings provided in a lower part of the rotor.
 7. A method for manufacturing a lined concrete pipe comprised of an outer concrete layer and an inner liner layer containing a further material which forms a greater density inner surface liner, said method comprising: providing an outer mould part and a core, a space formed between the outer mould part and the core having a shape of the lined concrete pipe, the core being movable upwardly through the outer mould part; providing a vibrator within the core, feeding concrete to the space formed between the outer mould part and the core as the core moves upwardly within the outer mould part for filling the space with concrete, providing the core with an applicator comprising one or more supply openings positioned for delivering the further material below the concrete supplied to the space, vibrating the concrete filling the space between the outer mould part and the core for maintaining the concrete in a fluid phase as the concrete is filling the space while simultaneously supplying the further material through the supply openings of the applicator for merging and diffusing the further material into the adjacent fluidized concrete, and at least partially rotating the applicator and the core during delivery of the concrete and further material for merging and diffusing the further material into the concrete adjacent the applicator to provide a sliding transition from the concrete and out to the further material, forming a mutually denser structural liner with a tight bond, the liner integrating together the concrete and further material, thereby forming an integral liner with the concrete pipe, providing a greater density surface on at least a portion of an inner surface of the concrete pipe; and, delivering the further material for applying the inner layer to a bottom ring and/or a top ring when said ring or rings have been connected with the core and outer mould part and before the space is filled with concrete.
 8. The method according to claim 7 wherein the applicator is integrally formed with the core or by an applicator unit in direct connection with the core.
 9. The method according to claim 7 wherein the further material is delivered in the form of a paste, powder or liquid.
 10. The method according to claim 7 wherein the one or more supply openings essentially extend in the longitudinal direction of the core.
 11. The method according to claim 7 further comprising forming the core with the one or more supply openings located along the circumference of the core at an upper end of the core.
 12. The method according to claim 7 wherein the applicator is in a form of a rotor, the rotor having the one or more supply openings provided in a lower part of the rotor.
 13. A method for manufacturing a lined concrete pipe comprised of an outer concrete layer and an inner liner layer containing a further material which forms a greater density inner surface liner, said method comprising: providing an outer mould part and a core, a space formed between the outer mould part and the core having a shape of the lined concrete pipe, the core being movable upwardly through the outer mould part; providing a vibrator within the core, feeding concrete to the space formed between the outer mould part and the core as the core moves upwardly within the outer mould part for filling the space with concrete, providing the core with an applicator comprising one or more supply openings positioned for delivering the further material below the concrete supplied to the space, vibrating the concrete filling the space between the outer mould part and the core for maintaining the concrete in a fluid phase as the concrete is filling the space while simultaneously supplying the further material through the supply openings of the applicator for merging and diffusing the further material into the adjacent fluidized concrete, and at least partially rotating the applicator and the core during delivery of the concrete and further material for merging and diffusing the further material into the concrete adjacent the applicator to provide a sliding transition from the concrete and out to the further material, forming a mutually denser structural liner with a tight bond, the liner integrating together the concrete and further material, thereby forming an integral liner with the concrete pipe, providing a greater density surface on at least a portion of an inner surface of the concrete pipe; and, wherein the pipe has a spigot end, and further comprising delivering the further material for applying an inner layer to the spigot end, lifting a top ring or a profile ring, filling the further material over the spigot end of the pipe, and then lowering/pressing down the profile ring over the spigot end simultaneous with or immediately following vibration.
 14. The method according to claim 13 wherein the applicator is integrally formed with the core or by an applicator unit in direct connection with the core.
 15. The method according to claim 13 wherein the further material is delivered in the form of a paste, powder or liquid.
 16. The method according to claim 13 wherein the one or more supply openings essentially extend in the longitudinal direction of the core.
 17. The method according to claim 13 further comprising forming the core with the one or more supply openings located along the circumference of the core at an upper end of the core.
 18. The method according to claim 13 wherein the applicator is in a form of a rotor, the rotor having the one or more supply openings provided in a lower part of the rotor. 